layer keyboard shortcut 2.83
After some experimentation, I found that the number keys correspond with the order of the collections (from top to bottom). By dragging your most-used collections to the top of the stack, it is easy to enable/disable a collection by pressing a number key.
Sadly, I can't show a picture of the other problem here. Basically: The old Layers grid is ALSO showing on my screen, taking up space, cluttering things up. I found no way to disable/remove it. I eventually uninstalled Blender 2.83.2 and rolled back to previous versions. All of them had the same problem until I got to 2.82a, where the Layers grid is not shown.
It's not all bad. I found that 2.82a is rock solid stable, unlike the 2.83 series, which crashes a lot. I'll stick with 2.82a for now.